Philosopher Rebecca Roache led a team of scholars at Oxford to think about the future of punishment. Aeon interviewed her about the project.

Roache: "Some crimes are so bad they require a really long period of punishment, and a lot of people seem to get out of that punishment by dying. And so I thought, why not make prison sentences for particularly odious criminals worse by extending their lives?"

One idea: Give prisoners drugs that make them experience a 1,000-year jail sentence in their mind.

Roache: "There are a number of psychoactive drugs that distort people’s sense of time, so you could imagine developing a pill or a liquid that made someone feel like they were serving a 1,000-year sentence. Of course, there is a widely held view that any amount of tinkering with a person’s brain is unacceptably invasive. But you might not need to interfere with the brain directly."

What about an eternal prison sentence, in other words, a Hell on Earth? Who would deserve such a sentence?

Roache: "Suppose there was some physics experiment that stood a decent chance of generating a black hole that could destroy the planet and all future generations. If someone deliberately set up an experiment like that, I could see that being the kind of supercrime that would justify an eternal sentence."